You might be thinking of the Mummy movies.
The original Mummy movie (from 1932) starts in 1921 then jumps ahead tens years. That would make it 1931. No problems yet.
The Mummy's Hand (1940) take place in May 1940. We're still good.
The Mummy's Tomb (1942) is said to take place 30 years after the Mummy's hand. So it would be in the 1970. At the end of the movie, a character receives his draft notice for World War II. So WWII lasted until the 70s in the Universal Monsters universe... or something.
The Mummy's Ghost (1944) is just two years after the Mummy's Tomb. So 1972.
The Mummy's Curse (1944) jumps ahead ANOTHER 25 years. So the Final Lon Chaney Jr Mummy movie, it would take place in 1997.
Bill Clinton was President, people were playing the Nintendo 64, DiCpario was starring in Titanic and the Mummy was rising from the Louisianan Swamps.
Behold, Fashions of the 90s.